حركات الإيماءات والنوابض

حركة تفاعلية فيزيائية

Animatable: تحكم منخفض المستوى

@Composable
fun BounceOnClick() {
    val scale = remember { Animatable(1f) }
    val scope = rememberCoroutineScope()
    Box(
        Modifier
            .graphicsLayer { scaleX = scale.value; scaleY = scale.value }
            .clickable {
                scope.launch {
                    scale.animateTo(1.3f, spring())
                    scale.animateTo(1f, spring())
                }
            }
    )
}

النوابض: dampingRatio وstiffness

val spec = spring<Float>(
    dampingRatio = Spring.DampingRatioLowBouncy,
    stiffness = Spring.StiffnessMedium
)

// later, inside a coroutine:
// offset.animateTo(targetValue = 0f, animationSpec = spec)

اكتشاف إيماءات السحب

@Composable
fun Draggable() {
    var offsetX by remember { mutableStateOf(0f) }
    Box(
        Modifier
            .offset { IntOffset(offsetX.roundToInt(), 0) }
            .size(80.dp)
            .background(Color.Red)
            .pointerInput(Unit) {
                detectDragGestures { change, drag ->
                    change.consume()
                    offsetX += drag.x
                }
            }
    )
}

العودة بارتداد نابضي

@Composable
fun SnapBack() {
    val offsetX = remember { Animatable(0f) }
    val scope = rememberCoroutineScope()
    Box(
        Modifier
            .offset { IntOffset(offsetX.value.roundToInt(), 0) }
            .size(80.dp)
            .background(Color.Blue)
            .pointerInput(Unit) {
                detectDragGestures(
                    onDrag = { change, drag ->
                        change.consume()
                        scope.launch { offsetX.snapTo(offsetX.value + drag.x) }
                    },
                    onDragEnd = {
                        scope.launch { offsetX.animateTo(0f, spring()) }
                    }
                )
            }
    )
}

الرمي بالسرعة

val decay = rememberSplineBasedDecay<Float>()

// on drag end, with measured velocity:
// scope.launch {
//     offsetX.animateDecay(
//         initialVelocity = velocity,
//         animationSpec = decay
//     )
// }

السحب للإغلاق باستخدام نقاط الارتكاز

enum class DragValue { Start, End }

val state = remember {
    AnchoredDraggableState(
        initialValue = DragValue.Start,
        anchors = DraggableAnchors {
            DragValue.Start at 0f
            DragValue.End at 300f
        }
    )
}

الحركات اللانهائية والمتكررة

@Composable
fun Pulse() {
    val transition = rememberInfiniteTransition(label = "pulse")
    val scale by transition.animateFloat(
        initialValue = 1f,
        targetValue = 1.2f,
        animationSpec = infiniteRepeatable(
            animation = tween(700),
            repeatMode = RepeatMode.Reverse
        ),
        label = "scale"
    )
    Box(Modifier.graphicsLayer { scaleX = scale; scaleY = scale })
}

الجمع بين الإيماءة والنابض

// pattern:
// 1) onDrag    -> animatable.snapTo(current + delta)
// 2) onDragEnd -> if (fast) animatable.animateDecay(velocity, decay)
//                 else      animatable.animateTo(nearestAnchor, spring())

الاستقرار النابضي باستخدام Kotlin خالص

fun main() {
    var pos = 0f
    var vel = 0f
    val target = 200f
    val stiffness = 0.2f
    val damping = 0.75f
    repeat(8) { step ->
        vel = (vel + (target - pos) * stiffness) * damping
        pos += vel
        println("step $step pos=${"%.1f".format(pos)}")
    }
}

النقر والضغط والإيماءات المتعددة

@Composable
fun LongPressScale() {
    val scale = remember { Animatable(1f) }
    val scope = rememberCoroutineScope()
    Box(
        Modifier
            .graphicsLayer { scaleX = scale.value; scaleY = scale.value }
            .pointerInput(Unit) {
                detectTapGestures(
                    onLongPress = {
                        scope.launch { scale.animateTo(1.4f, spring()) }
                    },
                    onPress = {
                        tryAwaitRelease()
                        scope.launch { scale.animateTo(1f, spring()) }
                    }
                )
            }
    )
}

تحقق سريع

مراجعة: الإيماءات والنوابض